1. Field of the Invention
The present invention relates to an ink, in particular, an ink used appropriately for an ink jet recording for recording on a recording medium by ejecting ink from an orifice in response to an ink recording signal, an ink set using the same, an ink cartridge, a recording unit, an image recorder and an image recording method.
2. Related Background Art
With respect to the ink jet recording technique, various ways have been thus far proposed, such as e.g., way to continuously generate changed ink droplets and use part of them for recording, way to give a signal to a recording head having a piezoelectric element and eject an ink in response to the signal or way to give thermal energy corresponding to a recording signal to the in-chamber ink of a recording head, e.g., by using an exothermic heater and eject an ink with the aid of the energy for recording. An ink jet recording method of way to eject an ink by using a foam phenomenon of ink due to thermal energy, for example, as described in Japanese Patent Application Laid-Open No. 54-59936 is a principal way in the current ink jet recording method from the viewpoint of easiness in highly integrating and highly concentrating of: the openings (hereinafter, referred to as xe2x80x9corificesxe2x80x9d) for ejecting an ink.
On the other hand, also as regards an ink for use in these ink jet recording techniques, various compositions, e.g., for obtaining images of better quality have been reported and proposed. Especially in recent years, for better recording on plain paper such as copy paper, report paper, note-book paper or letter paper, used generally in offices, and further cloth, an intensive research and development has been made from multifarious aspects such as ink composition and ink property.
Meanwhile, one of the characteristics which the ink preferably has as an ink for use in an ink-jet recording technique in which heat energy is applied to an ink by using an exothermic heater in response to a recording signal to eject the ink from an orifice, is that the ink causes no or litter foreign matters deposition, so called koge, on the exothermic heater during the recording process. With regard to an ink-jet recording process in which heat is applied to an ink to eject the ink from an orifice, foreign matters, koge, are tend to be deposited gradually on the surface of an exothermic heater, and the koge results in decrease of heat conductivity form the heater to the ink. The decrease in heat conductivity may cause some problems. For example, enough bubbles for ejecting the ink are not formed and certain amount of the ink necessary for proper recording is not ejected, or an ink ejection is completely stopped. That is, ink ejecting stability is disrupted.
For such a technological problem, an improvement in kogation by the content of oxo anions in ink has formerly been attempted, for example, in Japanese Patent Application Laid-Open No. 3-160070. Besides, Japanese Patent Application Laid-Open No. 9-151345 discloses a technique of inhibiting the occurrence of a scorch by the content of phytinic acid and its salts in ink. Furthermore, Japanese Patent Application Laid-Open No. 8-80664 discloses a technique of preventing kogation onto an exothermic head and promoting the jet durability by joint use of a liquid composition containing a cationic substance and bis-hydroxyethyl sulfone (BHES).
As a result of detailed examination on the problem of kogation in water-color ink, especially containing a water-soluble coloring material as color material, the inventors noticed a substantial improvement in scorching by addition of BHES but obtained acknowledge that there were cases where kogation different from formally occurred is deposited on an exothermic heater for a long-lasting time of recording. And from the subsequent study, they found that the relevant scorch contained sulfur, carbon and inorganic metals such as calcium and iron as well. In spite of there being cases where sulfur atoms exist as sulfonate group also in a water-soluble coloring material, hardly occurrence of kogation containing sulfur atoms was observed on an exothermic heater when not using BHES and therefore the inventors conjectured that this kogation is derived from BHES. The degree of the kogation is slight as compared with that caused by an ink which does not contain BHES ccurring on an exothermic heater in. However when the recording head of an ink jet recording apparatus is constructed so as to reduce an amount of ink ejected by one ejection action in order to meet the demand for a much better image, the amount of energy given to ink by an exothermic heater is decreased. In such a critical condition, even a minute kogation may fluctuate the amount of the ink ejected from the orifice, and the fluctuation would affect the recording of a highly defined image. Therefore, it was concluded that break through in the aforementioned problem was required in order to obtain a much higher quality image stably.
On the basis of further examination, the inventors found that the kogation can be very effectively inhibited even over a long period of recording by addition of at least one substance selected from dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates in water-color ink containing a water-soluble coloring material and BHES, thus leading to the present invention.
An object of the present invention is to provide an ink hardly affecting the exothermic heater on a change in ink jet performance in a long-time use for ink jet recording according to the way to eject an ink by using an exothermic heater.
Another object of the present invention is to provide an image recording method capable of stably recording an image excellent in quality even over a long time of recording.
A further object of the present invention is to provide an image recording apparatus capable of stably recording an image excellent in quality even over a long time of recording and an ink cartridge, an ink set and a recording unit usable therewith.
Still another object of the present invention is to provide such an ink that a long time of use for ink jet recording according to the way to eject an ink by using an exothermic heater hardly affects the heater to change in ink jet performance and that no ejecting of ink from orifices after a pause of recording hardly occurs even under various using environments or for further finer orifices.
Still further object of the present invention is to provide an image recording method capable of stably recording an image excellent in quality even over a long time of recording and capable of stably forming a high quality image even under multifarious using environments and capable of stably exhibiting the effectiveness even for finer orifices to attain a further higher quality of recording images.
Still another further object of the present invention is to provide an image recording apparatus capable of stably recording an image excellent in quality even over a long time of recording and capable of stably forming a high quality image even under multifarious using environments and capable of stably exhibiting the effectiveness even for finer orifices to attain a further higher quality of recording images and further an ink cartridge, an ink set and a recording unit usable therewith.
An ink according to one embodiment of the present invention attainable to the above object is characterized by containing at least one substance selected from the group consisting of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates, bis-hydroxyethyl sulfone and a water-soluble coloring material in an aqueous medium.
An ink according to another embodiment of the present invention attainable to the above object is characterized by containing at least one substance selected from the group consisting of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates, bis-hydroxyethyl sulfone and a coloring material wherein the total amount of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates, is not greater than 0.7% by weight relative to the whole weight of ink.
An ink cartridge according to one embodiment of the present invention attainable to the above object is characterized by comprising an ink housing section for housing ink containing at least one substance selected from the group consisting of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates, bis-hydroxyethyl sulfone and a water-soluble coloring material in an aqueous medium.
An ink cartridge according to another embodiment of the present invention attainable to the above object is characterized by comprising an ink housing section for housing ink containing at least one substance selected from the group consisting of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates, bis-hydroxyethyl sulfone and a water-soluble coloring material wherein the total amount of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates is not greater than 0.7% by weight relative to the whole weight of ink.
A recording unit according to one embodiment of the present invention attainable to the above object is characterized by comprising an ink housing section for housing ink containing at least one substance selected from the group consisting of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates, bis-hydroxyethyl sulfone and a water-soluble coloring material in an aqueous medium, means for giving the recording ink to a recording medium and means for supplying the ink to the above means.
A recording unit according to another embodiment of the present invention attainable to the above object is characterized by comprising an ink housing section for housing ink containing at least one substance selected from the group consisting of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates, bis-hydroxyethyl sulfone and a coloring material wherein the total amount of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates is not greater than 0.7% by weight relative to the whole weight of an ink; means for giving the recording ink to a recording medium; and means for supplying the ink to the above means.
An ink set according to another embodiment of the present invention attainable to the above object is characterized by comprising a combination of an ink containing at least one substance selected from the group consisting of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates, bis-hydroxyethyl sulfone and a first water-soluble coloring material in an aqueous medium and ink containing a second coloring material wherein each of the first and the second coloring materials is one selected from coloring materials such as; yellow, magenta, cyan, black, red, blue and green.
An image recording method according to one embodiment of the present invention attainable to the above object is characterized by comprising a process for giving an ink containing at least one substance selected from the group consisting of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates, bis-hydroxyethyl sulfone and a water-soluble coloring material in an aqueous medium to the image forming region of a to-be-recorded medium.
An image recording method according to another embodiment of the present invention attainable to the above object is characterized by comprising a process for giving an ink containing at least one substance selected from the group consisting of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates, bis-hydroxyethyl sulfone and a coloring material wherein the total amount of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates is not greater than 0.7% by weight relative to the whole weight of ink to an image forming region in a to-be-recorded medium.
An image recorder according to one embodiment of the present invention attainable to the above object is characterized by comprising an ink housing section for housing ink containing at least one substance selected from the group consisting of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates, bis-hydroxyethyl sulfone and a water-soluble coloring material in an aqueous medium, means for giving the recording ink to a to-be-recorded medium and a recording unit comprising means for supplying the ink to the above means; and means for actuating the recording unit in response to a recording signal.
An image recording apparatus according to another embodiment of the present invention attainable to the above object is characterized by comprising an ink housing section for housing ink containing at least one substance selected from the group consisting of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates, bis-hydroxyethyl sulfone and a coloring material wherein the total amount of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates is not greater than 0.7% by weight relative to the whole weight of ink; means for giving the recording ink to a to-be-recorded medium; and a recording unit comprising means for supplying the ink to the above means.
And, according to the individual embodiments mentioned above, images excellent in quality can be stably recorded over a long time with little change in ink jet performance even for a long duration of ink jet.
An image recording method according to one embodiment of the present invention attainable to the above object is characterized by comprising a process for allowing ink containing at least one substance selected from the group consisting of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates, bis-hydroxyethyl sulfone, urea and a water-soluble coloring material in an aqueous medium to the image forming region of a to-be-recorded medium wherein the total amount of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates, is not greater than 0.7% by weight relative to the whole weight of ink, to stick-to the image recording region of a recording medium by using a recording head so arranged as enable to eject 0.1 to 40 pl of ink from orifices by one time of jet operation.
An image recording apparatus according to one embodiment of the present invention attainable to the above object is characterized by comprising: an ink housing section for housing ink containing at least one substance selected from the group consisting of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates, bis-hydroxyethyl sulfone, urea and a water-soluble coloring material in an aqueous medium wherein the total amount of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates is not greater than 0.7% by weight relative to the whole weight of ink; a recording head equipped with means for ejecting the ink from orifices to a recording medium and means for supplying the ink to the recording head wherein said recording head is so arranged as able to eject 0.1 to 40 pl of ink from orifices by one time of jet operation; and means for actuating the recording unit in response to a recording signal.
A recording unit according to one embodiment of the present invention attainable to the above object is characterized by comprising: an ink housing section for housing ink containing at least one substance selected from the group consisting of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates, bis-hydroxyethyl sulfone, urea and a water-soluble coloring material in an aqueous medium wherein the total amount of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates is not greater than 0.7% by weight relative to the whole weight of ink; a recording head equipped with means for ejecting the ink from orifices to a recording medium; and means for supplying the ink to the recording head wherein said recording head is so arranged as enable to eject 0.1 to 40 pl of ink from orifices by one time of jet operation.
Besides, according to the individual embodiment mentioned above, images excellent in quality can be stably recorded over a long time with little change in ink jet performance even for a long duration of ink jet and further hardly any occurrence of clogging in orifices after a pause of recording even under various using environments or for further finer orifices.
(Operation)
With regard to the respective embodiments of the present invention, when allowing at least one substance selected from the group consisting of dicarboxylic acids, dicarboxylates, tricarboxylic acids and tricarboxylates to be contained in an aqueous ink containing water-soluble coloring material and BHES with individual embodiments of the present invention, it is considered, though the reason for an increase in the ink-jet stability of ink is obscure, that the property of koge formed on an exothermic heater changes by addition of these substances and the kogation is extremely minimized on account of its weak adhesion to the heater even if koge is deposited onto the heater.